Charge supporting means for furnaces



June 3, 1958 g, MUTH CHARGE SUPPORTING MEANS FOR FURNACES 2 Sheets-Sheet 1 Filed Dec. 1, 1953 F@. mmwmm\\ Inv ehtQr Robert C. Muth Maw His Attorn June 3, 1958 R. c. MUTH 2,837,326

CHARGE SUPPORTING MEANS FOR FURNACES Filed Dec. 1, 1953 2 Sheets-Sheet 2 Fig.5

' Robert C. Muth by AM EM His Attorney CHARGE surronrmo MEANS FOR FURNACES Robert C. Muth, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 1, 1953, Serial No. 395,342

8 Claims. (Cl. 263-40) This invention relates to metallurgical furnaces, and, in particular, to furnaces of the removable cover type commonly referred to as bell furnaces and to elevator type furnaces wherein the charge and its supporting hearth are raised into the furnace through the bottom thereof.

It is a usual practice in these types of furnaces to support the charge on a platform commonly referred to as a hearth which is in turn supported on the furnace base structure by means of a plurality of upright posts. The temperature of the hearth will normally vary over a wide range with the various heating and cooling operations and consequently, thermal expansion and contraction of the hearth will result. Although the hearth is in some cases not attached to the supporting posts but merely rests on the tops of these posts, the coefficient of friction between the hot metals is so high that the hearth will normally not slide on the posts as it expands or contracts with temperature. Therefore, if the posts are firmly afiixed to the furnace base, they will be subjected to repeated flexing as a result of the thermal expansion and contraction of the hearth, thus materially shortening the life of the posts.

This problem is even more aggravated in cases where the charge and the hearth are removed while still hot for cooling outside the furnace, leaving the posts in a bent condition. When the next charge and its supporting hearth are lowered onto the posts, the resulting thermal expansion deflects the posts even further, and failure of the posts is rapidly accelerated.

Attempts have been made in the past to solve this problem by pivoting the supporting posts to the base by means of conventional journal bearings so that each post could tilt back and forth in a single plane perpendicular to the axis of the bearing. The plane of tilting was then aligned as nearly as possible with the direction of the maximum thermal expansion and contraction, which in contraction in other directions and also any misalignment of the tilting plane from the direction of maximum movement will still result in a bending of the posts and will also cause additional loads on the pivot bearings. This problem is even more serious when the hearth is of rectangular shape since it is extremely difficult to predetermine the direction of thermal expansion, especially with a non-uniform loading of the charge on the surface of the hearth.

It is, therefore, an object of this invention to provide an improved means for supporting a charge in a furnace in which the posts which support the hearth are allowed to tilt in any direction upon thermal expansion or contraction of the hearth.

It is another object of this invention to provide an improved means for supporting a charge in an electric furnace in which the posts supporting the hearth can tilt a limited amount in any direction without exceeding the i re stable equilibrium region of the posts so that they will return to their initial position when the load on the posts is removed, thereby providing an inherently stable sup; porting structure for the hear It is a further object of this invention to provide an improved charge supporting means for a furnace in which the tilt of the hearth supporting posts in any direction is lmiited to a predetermined amount and in which novel means for enclosing and shielding the posts are provided to reduce radiation losses and to prevent insulation and other material from interfering with the tilting. action of the posts.

Briefly stated, in accordance with one aspect of this invention, each of the posts which support the furnace hearth on the base structure is provided with a flanged base portion. Each of these flanged base portions is provided with an annular groove on the underside thereof which engages an annular ring supported on the furnace base structure. When the post is not loaded, the groove engages the annular ring around the entire periphery thereof, and when a tilting moment is applied to the post, the groove will disengage from a portion of the periphery of the annular ring allowing the post to tilt in the direction of the tilting force applied. A plate memher is provided to engage the flanged base portion at a predetermined point to limit the, maximum tilt of the post. The diameter of the annular ring is made sufii-' ciently large so that the Weight of the post acting at its center of gravity still exerts a restoring moment when the post is in the maximum tilted position. Therefore, when the load on the post is removed, it will return to its initial position. An enclosing and shielding structure is provided around the post to reduce radiation losses and to prevent insulation and other foreign materials from interfering with the tilting action.

This invention will be better understood and other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

Referring to the drawings, Figure 1 is an elevational view, partly in cross section, of the base portion of a removable cover type furnace embodying this invention;

Figure 2 is a fragmentary end view of the furnace base structure enlarged to show the details of the supporting post structure in one embodiment of this invention;

Figure 3 is an enlarged perspective View of the supporting post base shown in Figure 2;

Figure 4 is an enlarged perspective view of a modified post base structure illustrating another embodiment-of this invention;

Figure 5 is a fragmentary view, partly in cross section, of a hearth supporting structure embodying this invention in which the hearth rests directly on the posts.

Referring to Figure l, a suitably insulated furnace bell or cover 1 rests on the furnacebase structure 2 and can be lifted from the base structure to allow access to the interior of the furnace. The furnace base structureis insulated by means of a powdered insulating material 3 which is enclosed along the top surface thereof by a layer of insulating concrete material 4. The charge is supported in the furnace on a hearth 5 which, in the configuration shown, is a grid type casting. The hearth 5 rests on a plurality of beam members 6, each of which extends between a pair of the supporting posts 7. As. shown in Figure 2, the beam members 6 rest in the-notches 8 ex-i tendin across the top of the supporting posts and are provided with eyelet portions for engaging the restraining pins 9. The pins 9 extend through oversized holes in the supporting posts 7 andserve to restrain any vertical move-: ment of the beam members 6 occasioned by the beam members sticking to the hearth when the hearth is re-- moved hot with the charge. A sufficient amount of looseness is provided in the engagement of the pins with the respective holes in the supporting posts to allow ample tilting of the posts without bending the restraining pins.

The supporting posts are made hollow in order to reduce the heat losses through the posts by conduction and are reduced in diameter at the lower portions thereof to further restrict the flow of heat. Each of the posts is provided with an enlarged base such as the flanged base portion which has an annular groove 11 extending along the underside thereof which in turn engages the bearing portion 12 of one of the annular bearing members 13 as shown in Figures 2 and 3. When a tilting force is applied to the post in any direction, the groove 11 can disengage from a portion of the bearing portion 12 to allow post to tilt in the direction of the force applied. Thus the supporting posts 7 can tilt in any direction with the thermal expansion and contraction of the hearth so that it becomes unnecessary to attempt to align a particular tilting plane with the direction of maximum thermal expansion and contraction of the hearth as has been the case with arrangements used in the past. In addition, all thermal expansion and contraction, regardless of the direction, is automatically compensated for, thus relieving all bending stresses in the posts and the additional hearing loads unavoidably present in arrangements heretofore used.

The diameter of the bearing portion 12 is made sufiiciently large so that a predetermined region of tilt is provided within which the Weight of the post acting through its center of gravity exerts a restoring moment tending to bring the post back to its initial position. Thus a stable equilibrium region is provided within which the post will return to its initial position of full engagement around the periphery of the bearing portion 12 with the groove 11 when the load on the post is removed. The stable equilibrium region of the posts is made sufficiently large so that the posts will not exceed the limits of this region in the normal tilting action that results from thermal expansion and contraction of the hearth. Thus, although the posts are freely tiltable in any direction, they provide a stable support upon which the hearth may rest without the benefit of any further restraints to keep it in position.

In addition, means are provided for limiting the amount of tilt of the posts to a predetermined maximum. As shown in Figures 2 and 3, the plate members 14- are positioned directly above the flanged base portions 10 so as to engage the flanged base portions upon a predetermined amount of tilt of the posts 7 and prevent further tilting.

The maximum tilt position is chosen so as to be within the stable equilibrium region of the posts, thereby ensuring that the posts are not overbalanced due to various incidental forces such as may result from a momentary sticking of the beam members 6 to the hearth 5 as the hearth is removed from the furnace. The plate members 14 also serve to limit the vertical movement of the posts resulting from the above-mentioned sticking action that may occur between the beam members and the hearth.

Each of the posts 7 is encircled by a shield member 15 which is made conical in shape in order to reduce the size of the aperture 16 and thereby minimize the cross sectional area through which radiation losses may pass from the interior of the furnace. The shield members 15 also provide insulation-free spaces within the insulating materials 3 and 4 within which the posts may tilt in any direction.

A cover plate 17 is attached to each of the posts and extends over the corresponding upper edge portion of each of the shield members 15 in order to prevent insulation and other foreign material from entering the spaces provided by the shield members 15 and interfering with the tilting action of the posts. The base portion of the post is enclosed and shielded from the insulating material 3 by means of the cylindrical member 18 and the plate member 14.

Another embodiment of this invention is shown in Figure 4 in which the posts 7 are supported on the furnace base structure by means of the flanged base portions 19 resting in turn on the annular bearing members 20. The bearing members 20 rest on the furnace base structure in the same manner as the bearing members 13 shown in Figures 2 and 3, and each is provided with a horizontally extending bearing surface 21 which cooperates with the underside of the flanged base portion 19 to permit a tilting a n of the posts. In this embodiment the post 7 is seine-red on the bearing member 20 by means of the conieally shaped member 22. The member 22 also serves to limit the maximum tilt of the post by engaging the outer surface of the bearing member 20 at a predetermined degree of tilt.

Figure 5 illustrates another embodiment of this invention wherein the post base structure shown in Figures 2 and 3 is utilized in a furnace in which the hearth 5 rests directly on the posts 7 instead of on the beam members (a as shown in Figures 1 and 2. In this case the supporting members 23, which are cast integrally with the hearth 5, engage the rounded heads 24 on the posts 7. It can be seen that the embodiment of the invention shown in Figure 4 is equally applicable to this type of arrangement.

It should also be apparent from the foregoing that the scope of this invention is not limited to the particular embodiments described, and that various changes, combinations, substitutions or modifications may be employed in accordance with these teachings without departing in spirit or in scope from this invention in its broader aspects.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Charge supporting means for a furnace comprising a hearth, a plurality of posts supporting said hearth, each of said posts comprising an upwardly extending portion and a flanged base portion extending transversely to said upwardly extending portion, a furnace base structure, a plurality of bearing members supported on said furnace base structure and each having an annular bearing portion extending along the upper portion thereof in a substantially horizontal direction, each of said bearing members interacting along the said bearing portion thereof with a dilferent one of said flanged base portions to support said posts on said furnace base structure and to permit a tilting action of said posts in any direction, and means for limiting the maximum tilting of said posts to a predetermined amount.

2. Charge supporting means for a furnace as defined in claim 1 wherein said means for limiting the maximum tilting of said posts to a predetermined amount comprises a plurality of substantially horizontally extending plate members, each of said plate members being supported by said furnace base structure directly above a different one of said post flanged base portions and engaging said post fianged base portions at a predetermined angle of tilt of said posts and preventing further tilting of said posts.

3. Charge supporting means for a furnace as defined in claim 1 wherein said means for limiting the maximum tilting of said posts to a predetermined amount comprises a plurality of conically shaped members, each of said conically shaped members extending down and flaring out in a downward direction from the lower surface of a different one of said post flanged base portions and each extending around the outside of a different one of said bearing members and engaging said bearing members at a predetermined angle of tilt of said posts and preventing further tilting of said posts.

4. Charge supporting means for a furnace comprising a hearth, a plurality of posts supporting said hearth, each of said posts comprising an upwardly extending portion and a flanged base portion extending in a substantially horizontal direction, a furnace base structure, a plurality of bearing means supported by said furnace base structure, each of said bearing means engaging the underside of a difierent one of said flanged base portions in supporting relationship thereto and cooperating therewith to allow said posts to tilt in any direction, a plurality of substantially conically shaped shield members, each of said shield members encircling a different one of said post upwardly extending portions and flaring out in an upward direction from the vicinity of the base portion thereof, and an insulating material supported on said furnace base structure and surrounding the outer surfaces of said shield members, said shield members providing a plurality of spaces within said insulating material within which said posts are free to tilt in any direction.

5. Charge supporting means for a furnace as defined in claim 4 wherein each of said posts has a cover plate attached thereto and extending over the corresponding upper edge portion of each of said substantially conically shaped shield members to prevent foreign material from entering the spaces provided by said shield members in said insulating material.

6. Charge supporting means for a furnace comprising a hearth, a furnace base structure, a plurality of hollow cylindrical posts extending substantially vertically intermediate said hearth and said base structure and supporting said hearth on the upper ends thereof, a plurality of substantially horizontally extending flange members affixed one each to the lower ends of said posts and each having an annular groove on the underside thereof coaxial with the aflixed post, a plurality of bearing members supported by said furnace base structure and each having an annular bearing surface thereon mating with a different one of said annular grooves on said flange members and cooperating therewith to permit said posts to tilt in any direction while preventing relative sliding movements between said bearing members and said flange members, a plurality of substantially horizontal plate members each supported by said base structure directly above a different one of said flange members and engaging said flange members upon a predetermined amount of tilt of said posts in any direction and preventing further tilting of said posts, a plurality of substantially conically shaped shield members, each of said shield members encircling a different one of said posts and flaring out in an upward direction from the vicinity of the base portion thereof, an insulating material supported on said base structure,

said shield members providing a plurality of spaces within said insulating material within which said posts are free to tilt in any direction, and a plurality of cover plates attached one each to said posts and extending over the corresponding upper edge portion of each of said shield members and preventing foreign material from entering the spaces provided by said shield members in said insulating material.

7. Charge supporting means for a furnace comprising a furnace base structure, a plurality of stationary bearing members on said base structure, each of said bearing members having a substantially horizontal annular bearing edge, a plurality of tiltable posts mounted on said bearing members and having a normally vertical position, each of said posts having an upwardly extending portion and a horizontal flanged base portion, each of said base portions resting on a corresponding annular bearing edge and forming a line of engagement therewith along which said posts are tiltable in any direction, said line of engagement being located so as to cause said posts to have a region to tilt Within which a moment is produced tending to restore said posts to said vertical position, and a removable hearth supported in a substantially horizontal position by said posts.

8. Charge supporting means as defined in claim 7 in which said base member has an annular groove in the underside thereof for receiving and engaging said annular bearing edge for preventing lateral shifting of said posts.

References Cited in the file of this patent UNITED STATES PATENTS 198,072 Bonzano Dec. 11, 1877 838,571 Numan Dec. 18, 1906 880,243 Rominger Feb. 25, 1908 1,266,152 Poole May 14, 1918 1,994,629 Arkema Mar. 19, 1935 2,414,996 Armstrong Jan. 28, 1947 2,434,692 Gauthier Jan. 20, 1948 2,446,948 Neutra Aug. 10, 1948 2,481,170 Spangler Sept. 6, 1949 2,485,995 Armstrong Oct. 25, 1949 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,837,326 June 3, 1958 Robert Co Muth It is hereby certified that error appears in the printed specification of the" above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 21, for "region to" read region of o Signed and sealed this 10th day of February 1959 SEAL) ttest:

KARL Ho AXI-INE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

